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Biomedical subjects

T Furuno

Publications and source records attributed to T Furuno.

98 records · Page 6Linked to original sources
PubMed1988

[Effects of local vibration exposure on whole blood viscosity in rats].

To investigate the relationship between vibration hazards and blood viscosity, vibration exposure experiments were conducted. The rat's hind limbs were continuously exposed to local vibration (60 Hz, 5 G) for 4 h. The exposed group showed a slightly lower blood viscosity and plasma fibrinogen in the blood obtained immediately after exposure when compared with the control group. However, in the blood obtained 18 h after exposure, there was no significant difference in the levels of whole blood viscosity and plasma fibrinogen between the exposed group and the control group. Hematocrit was not affected by this exposure. These results indicate that the decrease in the levels of whole blood viscosity induced by local vibration exposure is transient and that some relationship exists between changes of whole blood viscosity and those of plasma fibrinogen.

Animals↗
PubMed1988

Effects of low- and high-frequency local vibration on the occurrence of intimal thickening of the peripheral arteries of rats.

Rats were exposed to local vibration in a study of the differences in the effects between low and high frequencies of vibration on the vessel wall of peripheral arteries. The vibration was delivered at frequencies of 30 and 480 Hz under a constant acceleration of 5g. The duration of the vibration exposure was 30 d. The changes in the arteries were studied pathohistologically and hematologically. Three of the five rats exposed to 30 Hz and three of the five rats exposed to 480 Hz showed disruption of the internal elastic lamina. The disruption was followed by focal cell proliferation with regenerative formation of collagen and elastic fibers. The vascular changes observed after vibration exposure could not be explained by changes in plasma lipid concentrations. These results suggest that not only low frequencies of vibration, but also high frequencies have harmful effects on the intima of small arteries.

Animals↗
PubMed1987

Occurrence of intimal thickening of the peripheral arteries in response to local vibration.

Experiments were performed to elucidate a possible mechanism for the peripheral circulatory disturbance caused by vibration. Rats were exposed to local vibration (60 Hz, 5 G) on their hind legs for four hours a day for 30 days or 90 days. With exposure for 30 days the small arteries at the exposed site did not change. With exposure for 90 days, however, disruption of the internal elastic lamina was observed in the small arteries. This disruption was followed by focal cell proliferation with regenerative formation of collagen and elastic fibres. The fibrocellular thickening of the intima was further augmented, and in addition a complete stenosis of the lumen of the small arteries was observed. Electron micrography showed that the fibrocellular thickening of the intima consisted of a proliferation of arterial smooth muscle cells and numerous collagen and elastic fibres. These alterations were not observed in the arteries of the controls. The thickness of the media did not differ between the control and exposed groups or in animals with different durations of exposure. Concerning plasma total cholesterol, HDL-cholesterol, and lipoperoxide, there were no significant differences between the control and exposed groups after either 30 or 90 days, but the whole blood viscosity was significantly increased by day 90. This finding may be related to the intimal thickening.

Animals↗
PubMed1987

Usefulness of blood parameters, especially viscosity, for the diagnosis and elucidation of pathogenic mechanisms of the hand-arm vibration syndrome.

In the present study it was found that, in vibrating-tool operators with Raynaud's phenomenon, whole blood viscosity was significantly higher than in operators without Raynaud's phenomenon at shear rates from 230 to 11.5 s-1. In addition rats were experimentally exposed to local vibration (60 Hz, 5 g) on their hind limbs for 4 h/d for 30 or 90 d. In the case of 30-d exposure, the small arteries in the exposed site did not change. However, after exposure for 90 d, disruption of the internal elastic lamina was observed in the small arteries. The disruption was followed by focal cell proliferation with regenerative formation of collagen and elastic fibers. The fibro-cellular thickening of the intima was further augmented, and, in addition, a complete stenosis of the small lumen of the small artery was observed. Medial thickness did not show significant differences between the control and exposed groups for either exposure duration. The whole blood viscosity was significantly increased by the 90-d but not by the 30-d exposure. These results suggest that there are some relationships between the increase in whole blood viscosity and the intimal thickening of some small arteries in the exposed site.

Animals↗
PubMed1986

[Changes in the forearm tcPO2 following the cold water immersion test].

The purpose of this study is to apply changes in forearm transcutaneous PO2 (tcPO2) during the cold water immersion test (5 degrees C, for 10 min) to the diagnosis of vibration syndrome. Forearm tcPO2 in healthy controls increased gradually up to 3 min after the start of the cold water immersion and decreased thereafter. It returned to almost the same level before immersion 5 min after the start. In the workers using vibrating tools manifesting Raynaud's phenomenon, forearm tcPO2 also increased up to 3 min after the start as in healthy controls, but no change was observed thereafter. The difference between the level of forearm tcPO2 at 3 min and that at 10 min after the start of the immersion (Forearm tcPO2 recovery index, newly devised by authors) in workers using vibrating tools was significantly lower than that in healthy controls. Therefore, investigation of changes in forearm tcPO2 following the cold water immersion test is considered to be a useful objective item which can contribute to the diagnosis of vibration syndrome.

Aged↗
PubMed1984

Internal motion of DNA in bacteriophages.

We have investigated internal motion of DNA in bacteriophages by measuring fluorescence anisotropy decays of intercalated ethidium. The results showed large suppression of the internal motion of the inner DNA; the interhelix interaction of the DNA in the phage head is considered to enhance the effective viscosity of the DNA rod and to restrict the angle of the internal motion. Considering that the observed internal motion arises mainly from torsional motion of the DNA, we have calculated the movable angles of the torsional motion (the standard deviation of the torsional motion) of the DNA in the phage heads. The magnitude of the calculated movable angles indicates the extent of suppression of the DNA movement in the phage head; in lambda wild type phage, the DNA is packed most rigidly in the head and the motion is found to be restricted most severely. In a deletion mutant of lambda phage, whose inner DNA content is deficient by 17.6%, steric hindrance from the interhelix DNA interaction is decreased, and the DNA can move more easily. In T4 wild type phage, although the extent of condensation of the inner DNA is the same as that in lambda wild type phage, the DNA was fairly mobile. The presence of glucosylated hydroxymethylcytosine is suggested to influence the rigidity of the inner DNA or packaging mode of the DNA in the T4 head.

Animals↗
PubMed1983

Small-angle X-ray scattering study of adenosine triphosphatase from thermophilic bacterium PS3.

Adenosine triphosphatase from the thermophilic bacterium PS3(TF1) has been studied by solution X-ray scattering. A structural change in TF1 caused by the binding of ADP was observed by examining the difference between the radii of gyration of the unligated and ligated forms. The radius of gyration of the unligated TF1 was found to be 49.5 +/- 0.3 A, and it decreased by approximately 3% after ligation with ADP. The positions and the amplitudes of a subsidiary maximum and a shoulder in the scattering profile showed subtle change on nucleotide binding. The lower limit of the maximum length of TF1 was determined to be 165 A for the unligated form and 150 A for the ligated form. The shape analysis of TF1 was performed by model calculations for simple triaxial bodies or their complexes. Among the various models tested, the one that gave the best fit with the experimental data consisted of seven ellipsoids of revolution; six identical ellipsoids with semi-axes: a = b = 18.5 A and c = 74 A. arranged hexagonally, and the other with a = b = 28 A and c = 45 A, located below the other six on the 6-fold axis. On the basis of this model it was suggested that there is a structural change on ligation with nucleotides, consisting of a shrinkage of the six long ellipsoids by 6% along their major axes.

Adenosine Diphosphate↗